The present invention relates to a specific coupling reaction measuring method for measuring the content of a substance to be measured (hereinafter referred to as a subject substance) that may be included in a sample, and a reagent kit and a specific coupling reaction measuring apparatus for use in the specific coupling reaction measuring method.
In the field of medical care, the content of a protein peculiar to each disease present in a human body fluid is generally measured for diagnosis of various diseases or for examination of the progressing condition of a disease. In the measurement of the content of a protein, a specific coupling reaction measuring method utilizing a reaction between an antigen and an antibody for specifically recognizing a target protein as an antigen (namely, an antigen-antibody reaction) is widely used. Currently, a variety of specific coupling reaction measuring methods respectively based on various principles have been developed.
Among these various specific coupling reaction measuring methods, well-known measuring methods are immune nephelometry (hereinafter referred to simply as the nephelometry), immune turbidimetry (hereinafter referred to simply as the turbidimetry) and a slide agglutination in all of which agglutination of an antigen-antibody complex generated through an antigen-antibody reaction (hereinafter referred to as the agglutination complex) is detected in order to measure the content of a subject substance in a sample. In the antigen-antibody reaction, turbidity is caused in the reaction system due to the generation of the agglutination complex. The extent of the turbidity caused in the reaction system due to the generation of the agglutination complex depends upon the quantity of the antigen and the quantity of the antibody. On the basis of this, the extent of the turbidity caused in the reaction system is optically measured in the nephelometry and the turbidimetry, so as to calculate the quantity of the antigen or the antibody based on the optically measured value. Specifically, the agglutination complex is measured on the basis of change in the quantity of light scattered in the reaction system according to the nephelometry and is measured on the basis of change in the quantity of transmitted light reduced through the scattering in the reaction system according to the turbidimetry. In general, the same reaction system can be used in the measurement by these two methods. In other words, a reaction system that can be dealt with by one of these methods can be dealt with by the other method. In the slide agglutination, turbidity or aggregate caused in a reaction system due to generation of an agglutination complex is visually measured on a slide glass or the like. Also in the slide agglutination, the same reaction system as that usable in the nephelometry and the turbidimetry can be used. In these three measuring methods, the measurement is performed by using a reaction system in which an antigen and an antibody are homogeneously dispersed, and hence these methods are known generically as an “specific coupling reaction measuring method for a homogeneous system”.
Also, in the field of the medical care, the contents of several kinds of subject substances are measured for diagnosis of various diseases or for examination of the progressing condition of a disease. For example, in a clinical examination, the contents of all proteins in a humane urine are measured as an index of the filtering function of a kidney, or the content of erythrocyte (hemoglobin) in a humane urine is measured as an index of inflammation, calculosis or a tumor of a urinary tract such as acute glomerulonephritis, IgA nephropathy, nephrophthisis, renal infarction, interstitial nephritis, cystitis, urethritis or prostatitis (for example, see Non-Patent Document 1 below). Furthermore, Patent Document 2 below discloses, as a specific coupling reaction measuring method for a homogeneous system for measuring several kinds of subject substances, a method in which different reaction vessels are prepared for respective subject substances for individually measuring the subject substances.
It should be noted that methods of measuring the content of a subject substance in a sample by using a reaction of the subject substance included in the sample to a specific coupling substance for specifically coupling with the subject substance is referred to as “specific coupling reaction measuring method” in the present description. The aforementioned immune reaction measuring methods are also examples of the specific coupling reaction measuring methods.
Patent Document 1: Japanese Laid-Open Patent Publication No. 5-2024
Non-Patent Document 1: “Summary of clinical examinations”, written by Izumi Kanai, edited by Masamitsu Kanai, revised edition 31, published by Kanahara Shuppan Kabushiki Kaisha, 1998, p. 156 and pp. 179-180
However, in any of the aforementioned conventional methods, for measuring a plurality of kinds of subject substances, it is necessary to prepare reaction vessels in the same number as the number of kinds of subject substances, and hence a large quantity of sample is necessary.